Delayed splenic rupture following nonoperative management (NOM) in splenic injury is a rare complication. Resteghini et al. [
1] reported a case of splenectomy due to delayed splenic rupture after 2 months in a blunt abdominal trauma patient who had only minimal splenic contusion at the initial examination. Muroya et al. [
2] studied the delayed formation of splenic pseudoaneurysm (SPA) in patients with NOM in blunt splenic injury. In this study, delayed formation of SPA on follow up enhanced CT was confirmed at 15.4%, and timing was mean (SD) of 4.6 (2.1) hospital days (range, 1-8 days) after admission. About half of the SPA was occluded spontaneously without therapeutic intervention. They suggested that follow up enhanced CT for approximately 1 week after splenic injury may be useful for detecting delayed SPA formation. Splenic Pseudoaneurysm can be diagnosed when turbulent arterial flow is observed with color Doppler sonography in anechoic lesion on sonography [
3]. In the guideline of the World Society of Emergency Surgery for splenic trauma, the observation failure risk (OFR) computed tomographic (CT) scan criteria was included. Here, CT scan signs associated with high OFR are blush, pseudoaneurysm, OIS grade III with a large hemoperitoneum, and OIS grade IV or V [
4]. Brault-Noble et al. [
5] classified and treated 208 blunt splenic injuries using OFR CT scan criteria. NOM was performed in 161 (77%) and 49 (30%) had high OFR CT scan criteria. Thirteen patients (8%) experienced observation failure. In this study, high OFR CT scan criteria (odds ratio, 11.95: 95% confidence interval, 2.5-47.5) and the age of 50 years or older (odds ratio, 33.9: 95% confidence interval, 6.2-185.5) were independent factors related to observation failure. To reduce the morbidity and mortality associated with splenic trauma and subsequent delayed rupture, it is important for practitioner to have working knowledge of risk factors, diagnostic studies and interventions [
6]. In the present case, splenic injury was OIS II, and very small pseudoaneurysm was present on initial CT and increased to 2.5 cm on CT at 6th day of admission. On day 9, hemoglobin decreased by 1.9, and it was suspected to have been ruptured. Actually, splenic pseudoaneurysm rupture was confirmed by CT on day 13. Therefore, even the small splenic pseudoaneurysm need a careful and planned follow up plan.